RL24, RL28, and RL34 Trailable Yachts
from Rob Legg Yachts

RL Yacht Owner's Discussion Forum

Return to the Forum List

Outboard for RL28
My old high thrust 9.9 Yamaha is well overdue for replacement.
I have been looking at 9.9 hp Suzuki Honda and Yamaha (Merc Bigfoot will not fit through Bombay doors) all with high thrust props.
Can any one give advice on how they perform in comparison to each other.
I read in the engine survey on this site that most rl28 with Honda are 15hp.
Could this be they are using standard props or is it the 4 blade high thrust prop on the Honda's don't put out as much thrust as the 3 blade on the Yamaha?

Jason27-Apr-2014    Edit    Delete 
Re: Outboard for RL28
Most Honda 15 are the same size as the Honda 10 so people take the higher horspower model because there is not a significant price difference.

The mercury/Tohatsu 9.8hp outboard with high thrust propeller is also worth considering, its not thebig foot model but is more than enough outboard for the RL.

There is not a lot of difference between the various brands in terms of fuel consumption but if your running a fridge, charging capacity might be an issue.

Otherwise weight is worth considering unless you have a crane available when you need to lift the outboard out of the well.

I suspect the well will need to be cut to fit the large outboards like the Honda.
Greg 27-Apr-2014    Edit    Delete 
Re: Outboard for RL28
The Mercury 2 stroke 15hp outboard is far lighter than any of the 4 stroke motors and fits comfortably in the well without any hacking of the boat needed. The standard prop seems to work well in an RL28 so there is no need for the high thrust option. Two stroke motors do use more fuel than 4 stroke motors and you have to mix the oil in, but unless you do a lot of motoring they are much more suitable for light sailing boats. I could lift mine with one hand to get it out of the boat for servicing. The latest Honda 10/15 hp has an even wider cowling which makes it unsuitable without extensive modifications to the well.

Remember it is important to keep weight away from the ends of the boat as much as possible.

I know 2 strokes are out of favour now but I find the latest ones very reliable, no noisier than a 4 stroke, much lighter, and cheaper too. I think they are the better option unless you do a lot of motoring.

The disadvantages are higher fuel consumption, having to mix the oil into the fuel, and a lower output from the alternator.

Keith Merkley28-Apr-2014    Edit    Delete 
Re: Outboard for RL28
Kieth says you don't need a high thrust propeller.

Mercury did supply a change of propeller in the cost of the outboard. The standard propeller is designed for planing hulls and won't achieve close to full efficiency or full power without the high thrust propeller. then there is thevalue of the extra bite in reverse that is handy when around hazards.

Not having a high thrust propeller is like riding a pushbike in the high gear then wondering why your burnt out on gentle hills.

Whatever brand outboard, make sure you get the lowest pitch propeller available then you don't need to worry towing a dingy into a headwind with waves.
Greg 29-Apr-2014    Edit    Delete 
Re: Outboard for RL28
Thanks for the information Greg and Keith.
I had no idea choosing a new motor would be such a headache.

I should mention my boat is fitted with bombay doors and has a bracket which tilts the engine forward for the shaft to fit through the opening.

I'm in two minds about which way to go.
The 20 year old 9.9hp high thrust yamaha which suits my RL28 beautifully (great in astern, 7 knots ahead with power to spare) and having had a 8hp 2 stroke standard tohatsu in my previous boat which was a great engine but not great in reverse, I am keen to stick with what I know works in the Yamaha. Problem is they no longer make the high thrust in a short shaft.
Only Yamaha and Merc make true 9.8 hp high thrust geared outboards and only in long shaft or extra long.
So my options are to go for a standard 4 stroke s/s and have a high thrust prop fitted but not the gearing or modify my boat to fit the long shaft yamaha which is a bit smaller than the Merc and cheaper.

I really like the 4 stroke 9.8 Tohatsu s/s which is great on price but am unsure of how well a non geared high thrust prop will work compared to the yamaha.

So if anyone has fitted a high thrust prop to a standard motor or fitted a long shaft motor to a well with bombay doors please share your thoughts!

Jason1-May-2014    Edit    Delete 
Re: Outboard for RL28
for what it is worth I have a 2011 2 stroke Tohatsu 9.8 that works OK. It has a 4 blade high thrust prop on it. Pushes us along at max 6 knots, usually around 5.
Alister5-May-2014    Edit    Delete 
Re: Outboard for RL28
I am in the process of getting a new outboard fitted. My preference is four stroke as it is less noisy, less smoky, uses less fuel and is design ended to operate at low/medium revs unlike two stroke which like to rev out. Majority of motoring I do is around quater reves as I find pouring more fuel in doesn't make us go much faster. Hi thrust prop essential to get any reasonable amount of reverse. My mechanic is putting in a short shaft Merc 9.9, mainly because he is a dealer for these motors. He is having to make a few modifications to get the motor to tilt and release with the restrictions of the well. Looking forward to trying it out. Pete
Peter Corser9-May-2014    Edit    Delete 
Re: Outboard for RL28
Thanks Alister and Peter for the information,
I was unable to find a way to make the high thrust long shaft yamaha fit in the well so I have gone with the Tohatsu short shaft and will fit a high thrust prop.
The up side to this is that the gear case in the tohatsu is smaller making the length of the shaft about 80mm shorter than the current 20 year old yamaha. The cavitation plate depth is the same depth as the old Yamaha.
Thus the new engine will tilt through the Bombay doors without using the tilt forward bracket meaning i can have electric tilt.
Incidentally I live in Tasmania and went to Agfest (Hugh agricultural Expo) which had 4 marine dealers (go figure) from my area.
Managed to get the 4 stroke 9.8 hp tohatsu with electric start, power tilt and a high thrust prop for about $800 less than a standard (not high thrust geared) pull start yamaha. Had no idea such savings could be made at expos or boat shows!
Jason12-May-2014    Edit    Delete 
Re: Outboard for RL28
I did a lot of research into this recently, and I came up with what I considered to be the best option.
A Honda BF20X. Its a Honda 20hp four stroke, with an extra long leg, specifically designed for trailer sailers and house boats.
It had electric start, forward controls and hydraulic engine tilt.
The cost, brand new, was $5,500.
I was very tempted to go down the track of installing an outboard, but ended up deciding to rebuild the Volvo Penta instead.
Garry Beattie27-Jul-2014    Edit    Delete 

Return to the Forum List       Add a message to this discussion